Fixed several bugs that were triggering the issues we saw on portal.
Also, fixed a bug that blocked controller disabling.
diff --git a/xos/core/models/instance.py b/xos/core/models/instance.py
index 62a86c4..684fcdc 100644
--- a/xos/core/models/instance.py
+++ b/xos/core/models/instance.py
@@ -101,6 +101,9 @@
     volumes = models.TextField(null=True, blank=True, help_text="Comma-separated list of directories to expose to parent context")
     parent = models.ForeignKey("Instance", null=True, blank=True, help_text="Parent Instance for containers nested inside of VMs")
 
+    def get_controller (self):
+        return node.site_deployment.controller
+
     def __unicode__(self):
         if self.name and Slice.objects.filter(id=self.slice_id) and (self.name != self.slice.name):
             # NOTE: The weird check on self.slice_id was due to a problem when